From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f181.google.com (mail-ie0-f181.google.com [209.85.223.181]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 38D8E21F0F2 for ; Sun, 13 Jan 2013 22:14:16 -0800 (PST) Received: by mail-ie0-f181.google.com with SMTP id 16so4608489iea.12 for ; Sun, 13 Jan 2013 22:14:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=pWsCPc31Ae3FX0U4cSELblaedOsKHfTylmrFnD2OUiE=; b=Cynvx0rPdQaI5BJ3Prgq6AS+r+5IoqgkEkZpku0n5XSLufYEnDNkcYVEj5jAg/zQAW 2R+dwaidjI+YSTHzAtLTHL/D9EGbxGfaEOGZrOXFodWfU6kraLJAkZ0uGxHPk/llShgp GO1q9LL1xHBAuXYAatUdk+vEbDsTr81qbg1OsXDgcz809Btmh02Xl+6BdUoijn2kZAo9 zq5bvETCWlsnIG+0eGhTJJ/+meG5k1W8j5BdSOf6v/SEqrQ6aUis+FiGGhiCYdZT0uyC GcltmXDm64m4jtpTEczSPKsxAeY4hgB0HgGssFvSa2mr7BvRvS//fUn0SKeC3KX4Fgw5 C6qA== MIME-Version: 1.0 Received: by 10.50.196.164 with SMTP id in4mr5716016igc.86.1358144055624; Sun, 13 Jan 2013 22:14:15 -0800 (PST) Received: by 10.64.135.39 with HTTP; Sun, 13 Jan 2013 22:14:15 -0800 (PST) In-Reply-To: References: <50F32981.9080404@openwrt.org> Date: Sun, 13 Jan 2013 22:14:15 -0800 Message-ID: From: Dave Taht To: Ketan Kulkarni Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Eric Dumazet , Yuchung Cheng , cerowrt-devel Subject: Re: [Cerowrt-devel] TFO crashes cerowrt 3.7.1-1 X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 14 Jan 2013 06:14:16 -0000 I am so buried as to only be able to do new builds of cero once a week. Can the bad behavior be duplicated on a single core other sort of processor, like x86? Or merely boot up a x86 box in a single processor mode? I'll try to get a new release out next sunday. On Sun, Jan 13, 2013 at 8:43 PM, Ketan Kulkarni wrote: > Thanks Eric and Yuchung for taking care of the patch. I will test few mor= e > TFO cases as well once this patch is built in cero. > > Thanks, > Ketan > > On Jan 14, 2013 9:37 AM, "Eric Dumazet" wrote: >> >> Quite frankly I would just remove the BUG_ON() >> >> diff --git a/net/core/request_sock.c b/net/core/request_sock.c >> index c31d9e8..4425148 100644 >> --- a/net/core/request_sock.c >> +++ b/net/core/request_sock.c >> @@ -186,8 +186,6 @@ void reqsk_fastopen_remove(struct sock *sk, struct >> request_sock *req, >> struct fastopen_queue *fastopenq =3D >> inet_csk(lsk)->icsk_accept_queue.fastopenq; >> >> - BUG_ON(!spin_is_locked(&sk->sk_lock.slock) && >> !sock_owned_by_user(sk)); >> - >> tcp_sk(sk)->fastopen_rsk =3D NULL; >> spin_lock_bh(&fastopenq->lock); >> fastopenq->qlen--; >> >> >> >> On Sun, Jan 13, 2013 at 7:05 PM, Eric Dumazet wrot= e: >>> >>> Oh well yes, this doesnt quite work on !SMP. >>> >>> And this kind of bug is frequent.... >>> >>> See following example : >>> >>> commit b9980cdcf2524c5fe15d8cbae9c97b3ed6385563 >>> Author: Hugh Dickins >>> Date: Wed Feb 8 17:13:40 2012 -0800 >>> >>> mm: fix UP THP spin_is_locked BUGs >>> >>> Fix CONFIG_TRANSPARENT_HUGEPAGE=3Dy CONFIG_SMP=3Dn CONFIG_DEBUG_VM= =3Dy >>> CONFIG_DEBUG_SPINLOCK=3Dn kernel: spin_is_locked() is then always >>> false, >>> and so triggers some BUGs in Transparent HugePage codepaths. >>> >>> asm-generic/bug.h mentions this problem, and provides a >>> WARN_ON_SMP(x); >>> but being too lazy to add VM_BUG_ON_SMP, BUG_ON_SMP, >>> WARN_ON_SMP_ONCE, >>> VM_WARN_ON_SMP_ONCE, just test NR_CPUS !=3D 1 in the existing >>> VM_BUG_ONs. >>> >>> Signed-off-by: Hugh Dickins >>> Cc: Andrea Arcangeli >>> Cc: >>> Signed-off-by: Andrew Morton >>> Signed-off-by: Linus Torvalds >>> >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index b3ffc21..91d3efb 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -2083,7 +2083,7 @@ static void collect_mm_slot(struct mm_slot >>> *mm_slot) >>> { >>> struct mm_struct *mm =3D mm_slot->mm; >>> >>> - VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); >>> + VM_BUG_ON(NR_CPUS !=3D 1 && !spin_is_locked(&khugepaged_mm_lock= )); >>> >>> >>> >>> >>> On Sun, Jan 13, 2013 at 1:39 PM, Felix Fietkau wrote: >>>> >>>> On 2013-01-13 7:03 PM, Eric Dumazet wrote: >>>> > I suspect a bug in the spin_is_locked() implementation on your arch, >>>> > as >>>> > he socket lock should be held at this point. >>>> I don't think this is an arch implementation bug, this probably happen= s >>>> on all !SMP systems. See this bit from include/linux/spinlock_up.h: >>>> >>>> #define arch_spin_is_locked(lock) ((void)(lock), 0) >>>> >>>> - Felix >>>> >>> >> > > > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel > --=20 Dave T=E4ht Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.= html